Light emitting device system comprising a remote control signal receiver and driver

Abstract

The invention relates to a light emitting device system (112) comprising power supply terminals (114) and a remote control signal receiver (118), the power supply terminals being adapted for receiving electrical power from an external driver (100), the remote control signal receiver (118) being adapted for receiving a remote control signal, wherein the light emitting device system (112) is further adapted for providing the received remote control signal as remote control signal information exclusively via the power supply terminals (114) and/or via wireless transmission to the driver (100).

Claims

1. A light emitting device system, comprising: at least one light emitting device; power supply terminals connected to receive electrical power from an external driver and to supply the electrical power to the at least one light emitting device; a remote control signal receiver configured to receive a remote control signal selecting at least one light emission characteristic for the at least one light emitting device; and a circuit configured to provide via the power supply terminals to the external driver remote control signal information indicating the at least one selected light emission characteristic for the at least one light emitting device.

2. The light emitting device system of claim 1, wherein the remote control signal receiver faces in the direction of an illumination beam path of the light emitting device system.

3. The light emitting device system of claim 2, wherein the remote control signal receiver is spatially located in the illumination beam path of the light emitting device system.

4. The light emitting device system of claim 3, wherein the light emitting device system further comprises an optical lens, wherein the remote control signal receiver is located on the optical axis of said lens.

5. The light emitting device system of claim 1, wherein the circuit comprises an emulation circuit connected to the power supply terminals and configured to provide the remote control signal information via the power supply terminals to the external driver by emulating an electrical load of the light emitting device system.

6. The light emitting device system of claim 5, wherein the power supply terminals are configured to sequentially receive electrical power having a first power characteristic, and electrical power having a second power signal characteristic, wherein the emulation circuit is configured to more closely emulate the electrical load when receiving the electrical power having the second power signal characteristic than when receiving the electrical power having the first power signal characteristic.

7. The light emitting device system of claim 5, wherein the emulation circuit is configured to emulate the electrical load of the light emitting device system with respect to a potential which is different from the potential of the power supply terminals.

8. The light emitting device system of claim 5, wherein the emulation circuit comprises a variable resistance device connected across the power supply terminals, the variable resistance device having a control terminal connected to an output of the remote control signal receiver, wherein the remote control signal receiver changes an impedance of the variable resistance device to communicate to the external driver the remote control signal information indicating the at least one selected light emission characteristic for the at least one light emitting device.

9. The light emitting device system of claim 8, wherein the variable resistance device comprises a transistor connected across the power supply terminals.

10. The light emitting device system of claim 8, further comprising a resonant circuit connected in series with the variable resistance device across the power supply terminals.

11. A method, comprising: receiving, at power supply terminals of a light emitting device system which includes at least one light emitting device, electrical power from an external driver; supplying the electrical power from the power supply terminals to the at least one light emitting device; receiving at the light emitting device system a remote control signal selecting at least one light emission characteristic for the at least one light emitting device; and providing remote control signal information indicating the at least one selected light emission characteristic for the at least one light emitting device from the light emitting device system to the external driver via at least one of: (1) the power supply terminals, and (2) wireless transmission.

12. The method of claim 11, including providing via the power supply terminals to the external driver remote control signal information indicating the at least one selected light emission characteristic for the at least one light emitting device.

13. The method of claim 12, wherein the providing via the power supply terminals to the external driver remote control signal information indicating the at least one selected light emission characteristic for the at least one light emitting device includes varying an electrical load of the light emitting device system across the power supply terminals in response to the remote control signal to communicate the remote control signal information to the external driver.

14. The method of claim 13, wherein the varying an electrical load of the light emitting device system in response to the remote control signal includes switching on and off a transistor connected across the power supply terminals to communicate the remote control signal information to the external driver.

15. The method of claim 13, wherein the light emitting device system includes a metal housing wherein varying an electrical load of the light emitting device system in response to the remote control signal includes alternately connecting one of the power supply terminals to the metal housing and disconnecting the one of the power supply terminals to the metal housing.

16. The method of claim 13, wherein the receiving, at the power supply terminals of the light emitting device system, the electrical power from the external driver includes receiving the electrical power at a first frequency in a first time period, and receiving the electrical power at a second frequency in a second time period, wherein the electrical load is varied greater during the second time period in response to the remote control signal than in the first time period to communicate the remote control signal information to the external driver during the second time period.

17. The method of claim 11, including providing via wireless transmission from the light emitting device system to the external driver remote control signal information indicating the at least one selected light emission characteristic for the at least one light emitting device.

18. A method, comprising: supplying electrical power from a driver to an external light emitting device system via power terminals of the driver; receiving at the driver, via at least one of: (1) the power supply terminals and (2) wireless reception, remote control information communicated by the external light emitting device to the driver indicating at least one selected light emission characteristic for at least one light emitting device of the external light emitting device system; and the driver employing the remote control signal information to control a parameter of the electrical power supplied from the driver to the external light emitting device system to cause the at least one light emitting device of the external lighting emitting device system to provide the at least one selected light emission characteristic.

19. The method of claim 18, including receiving at the driver, via the power supply terminals, the remote control information communicated by the external light emitting device to the driver indicating at least one selected light emission characteristic for at least one light emitting device of the external light emitting device system.

20. The method of claim 19, wherein the receiving at the driver, via the power supply terminals, the remote control information communicated by the external light emitting device to the driver includes detecting changes in an impedance across the power supply terminals presented by the external light emitting device to the driver.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, preferred embodiments of the invention are described in greater detail by way of example only, with reference to the drawings, in which:

(2) FIG. 1 is a block diagram illustrating a light emitting device system and a driver,

(3) FIG. 2 is a schematic illustrating a circuit diagram of a driver and a light emitting device system,

(4) FIG. 3 is a further schematic illustrating a circuit diagram of a further driver and a further light emitting device system,

(5) FIG. 4 is a flowchart illustrating a method of operating a light emitting device system and a driver,

(6) FIG. 5 is a schematic illustrating various light emitting device systems.

DETAILED DESCRIPTION

(7) In the following, similar elements are denoted by the same reference numerals.

(8) FIG. 1 is a block diagram illustrating a driver 100 and a light emitting device system 112. The driver comprises a power supply 102 and power supply terminals 108. The light emitting device system comprises power supply terminals 114, wherein the power supply terminals 108 of the driver 100 and the power supply terminals 114 of the light emitting device system 112 are connected by means of a cable 110. Alternatively, instead of a cable other means could be used for the connection 110, e.g. a lighting rail system.

(9) The light emitting device system comprises a solid state light source, which may for example be a conventional light emitting diode (LED) or for example an organic light emitting diode (OLED).

(10) In order to operate the light emitting device system 112, the driver 100 supplies electrical power via the power supply terminals 108, the cable 110 and the power supply terminals 114 to a light emitting diode 116.

(11) The light emitting device system 112 further comprises a remote control signal receiver 118 which may be for example an infrared signal receiver or a radio frequency signal receiver. In case the receiver 118 receives a remote control signal from a remote control signal transmitter not shown in FIG. 1, e.g. a signal indicating a desired light emission characteristic like for example a certain light intensity, the receiver 118 will report this signal to an emulation module 120.

(12) The emulation module 120 comprises a controller 122 and a circuit 124. In the embodiment of FIG. 1, the controller 122 is an active controller comprising for example a processor. The controller 122 may receive the remote control signal from the receiver 118 and recognize a desired adjustment of the light emission intensity by a user.

(13) The controller 122 is further adapted for modulation of the impedance of the light emitting device system 112 via the circuit 124. The modulation of the impedance can be performed prior and/or during operation of the light emitting device system 112 to communicate data to the driver 100. For example, the circuit 124 comprises a controllable resistor, e.g. a MOSFET, wherein the resistance is modulated in accordance with the information to be provided to the driver 100, i.e. the remote control signal information. In the present example, the controller 122 detects a desired change of the light emission intensity, and the controller 122 tunes the circuit 124 for a respective impedance variation in order to communicate the desired change of the light emission intensity as remote control signal information to the driver.

(14) While providing electrical power to the light emitting device system 112, the driver 100 detects the impedance variation of the light emitting device system 112 via the supply terminals 108, the cable 110 and the supply terminals 114. The detection of the impedance variation is performed by means of a detector 106 of the driver 100. In other words, the detector 106 captures the remote control signal information change of light emission intensity by sensing a respectively assigned variation of the electrical load of the light emitting device system 112. In response, a controller 104 of the driver 100 controls the power supplied by means of the power supply 102, depending on the received remote control signal information. For example, the controller 104 may control the power supply 102 to reduce the electrical power supplied to the light emitting device system 112, which will lead to a certain light intensity attenuation of the light emitted by the LED 116 of the LED system 112.

(15) Further illustrated in FIG. 1 is a network 126, which can be for example a superordinate control network. If the network is present, the remote control signal information detected by the driver 100 may also be forwarded to the network 106. If several luminaires are employed comprising different drivers and LED systems with this feature, a distributed remote control receiver can be built. In such a case, the driver may change the signal by including additional information into the forwarded remote control signal information, which allows the control network to determine the driver and hence the location where the signal was received from.

(16) For example, a data processing system like a personal computer (PC) 128 may be part of the network and can be used in real time to display the actually set light emission characteristics of the LED system 112. In case the receiver 118 of the LED system 112 detects a remote control signal that indicates a desired change of the light emission characteristics of the LED 116, this information is provided to the PC 128 via the driver 100 and the network 126. Either the driver may automatically set the desired light emission characteristics of the LED by appropriately adjusting the power supplied via the terminals 108 and 114 to the LED system 112, or the PC 128 may adjust the power supply characteristics of the driver 100.

(17) Nevertheless, in both cases, since a preset and logical relationship exists between received remote control signals and said power supply characteristics, the PC 128 is always able to provide information about the actual light emission characteristics of the LED system 112.

(18) It has to be noted that additionally it is possible to provide the LED system 112 with one or more sensors which may sense the actual operating condition of the LED system 112. Such an operating condition may comprise, without loss of generality, an actual light emission characteristic of the light emitting device system and/or a temperature of the light emitting device system and/or an environmental condition of the environment in which a light emitting device system is being operated and/or a time of operation of the light emitting device system. For this purpose, various kinds of sensors may be used in the light emitting device system 112. These sensors may include for example temperature sensors, sensors which can sense the environmental conditions of the environment in which the light emitting device system is operated, for example a light sensor, humidity sensor, dust sensor, fog sensor or a proximity sensor.

(19) Further, it has to be noted that instead of using the cable 110 and the terminals 108 and 114 to provide the remote control signal information from the LED system to the driver, it is also possible to provide the LED system 112 with means 113 for wireless signal transmission and the driver 100 with means 109 for wireless signal reception. For example, the LED system 112 may transmit the remote control signal information via radio frequency (RF) transmission to the driver 100. Also, optical transmission of information or ultrasonic data transmission is possible, wherein in the latter case preferably the driver 100 and the LED system 112 comprise a common housing through which an ultrasonic coupling is provided

(20) In case wireless transmission is used, a requirement to be met is that the transmission characteristics like RF frequency and amplitude are selected in such a manner that undisturbed communication of data from the LED system 112 to the driver 100 is possible, which includes considering possible disturbances like metallic components of the driver 100, shielding by certain driver housing materials and the distance between the driver and the LED system. For example, the receiver 118 may receive an RF remote control signal in a first frequency range and provide respective remote control signal information in a second RF frequency range to the driver 100.

(21) FIG. 2 is a schematic view of a circuit diagram of the driver 100 and the light emitting device system 112. The driver 100 comprises a current source 102. The light emitting device system 112 comprises a set of light emitting diodes 116 in serial connection with each other. These series-connected diodes form an LED string. The current source 102 and the light emitting diodes 116 are connected via power supply terminals 108 and 114 by means of wires 110 which may also include connectors and respective sockets.

(22) In addition to the light emitting diode string comprising the light emitting diodes 116, the light emitting device system 112 further comprises a circuit 208 which comprises a resistor 204 and a transistor 206. The resistor 204 and the transistor 206 are arranged in series with respect to each other. The circuit 208 is arranged in parallel with the light emitting diode string comprising the LEDs 116. The light emitting device system further comprises a receiver 118 which comprises an infrared sensitive diode 202 and an amplifier 200. In the simple embodiment depicted in FIG. 2, in case a remote control signal, which may be an infrared light in a certain optical wavelength range, is provided to the photodiode 202, the photodiode 202 generates a photocurrent which is amplified by means of the amplifier 200. This amplified signal is provided to the transistor 206 of the circuit 208. In turn, an electrical current can flow from the top power supply terminal 114 of the light emitting device system to the lower power supply terminal 114 of the light emitting device system, thus changing the impedance of the system 112.

(23) In a variant of the structure shown in FIG. 2, it is possible to use an inductor instead of the resistor 204. Then, one or more additional free-wheeling diodes are required to feed the energy stored in the inductor during the activation time of the switch back to the LED string 116. With such an arrangement, the effect of the forwarded remote control signal on the average brightness of the LED string is reduced, since the energy taken from the supply terminal is not dissipated but fed back to the LEDs.

(24) This impedance change can be detected by the detector 106 of the driver 100. In the embodiment depicted in FIG. 2, the detector 106 may use this remote control signal information received via the change of the measured impedance and instruct the power source 102 to adjust the power output characteristics. In this case, the controller 104 of FIG. 1 may be included in the detector 106 or vice versa.

(25) It has to be noted that it is possible that the remote control signal received at the receiver 118 may be translated from one coding scheme into a different format which is better suited for the further handling of the information. For example, it is either possible to perform such a translation in a receiver unit 210, which comprises the receiver 118 and a circuit 208, or it is possible to perform the translation in the detector 106, e.g. it is possible to translate a received RC5 code into a I.sup.2C message.

(26) FIG. 3 is a further schematic view of a circuit diagram of a driver 100 and the light emitting device system 112. Again, the driver comprises a current source 102 and a detector 106, as well as the power terminals 108. The light emitting device system 112 comprises diodes 106 which form an LED string, as already discussed with respect to FIG. 2. The current source 102 and the light emitting diode 116 are connected via the power supply terminals 108 and 114 by means of wires 110.

(27) In addition to the light emitting diode string comprising the light emitting diodes 116, the light emitting device system 112 further comprises a circuit 308. The circuit 308 comprises an impedance 302, a capacitance 304 and a variable resistor 306, which are arranged in series with respect to each other. The circuit 308 is arranged in parallel with the light emitting diode string. The circuit 308 acts as frequency selection circuitry whose impedance can be tuned by means of the variable resistor 306. However, it has to be noted that the circuit 308 may be any circuit which is adapted to emulate a predefined impedance when receiving electrical power with the predefined power signal characteristic, which may for example comprise a certain frequency range as will be further described, without loss of generality, in this example.

(28) In normal steady state DC operation, the circuitry 308 will not influence the power delivered to the light emitting diode string comprising the diodes 116. However, with a dedicated driver 100, the impedance of the circuitry 308 can be detected. For this purpose, the power supply 102 can be switched from DC operation to AC operation via the detector 106, which comprises a respective controller, not shown here. At a certain frequency and voltage amplitude provided as electrical power to the light emitting device system 112, a certain current will flow through the circuitry 308, since the circuitry 308 becomes resonant. By sensing the impedance at one or several discrete frequencies or by sensing the impedance during a frequency sweep or by applying pulses to measure the frequency response, the impedance emulated by the light emitting device system 112 using the circuitry 308 can be detected.

(29) It has to be noted that instead of using a separate detector 106, it is possible to incorporate the detector in a control loop of the power source 102. The modulation of the load will introduce a short term deviation in the LED voltage or current. In case the driver has a closed loop control power supply, the modulation will be present in the error signal of the control loop. As a result, no extra sensing means are required in the driver.

(30) In case the impedance of the receiver unit 210 has to be detected independently of the impedance of the light emitting diode string comprising the diodes 116, the effect of the light emitting diodes may be compensated in the control circuitry of the driver 100. A further solution would be to deactivate the current source and only use a small sensing voltage, which does not reach the forward voltage of the light emitting diode string but is sufficient to sense the electrical load due to the presence of the circuit 308. In such a case, short sensing intervals are preferred to avoid visible artifacts in the light output of the light emitting diode string. Further, such an embodiment is preferred when the light emitting diode system is in the off state and waiting to receive a certain remote control signal, causing it to be powered up to the on state.

(31) A difference between the embodiments of FIGS. 2 and 3 is that in FIG. 2 an IR photodiode 202 is used for detecting a remote control signal, whereas in the embodiment of FIG. 3 an RF antenna 300 is used to receive a respective RF remote control signal.

(32) In the embodiments of FIGS. 2 and 3 it was assumed that remote control signal information is provided via the terminals 108, 114 and the wire 110. However, as already mentioned above, it is also possible to substitute the circuit 208 in FIG. 2 and the circuit 308 in FIG. 3 with wireless data transmission means and to substitute the detector 106 with wireless reception means, which allows transmission of remote control signal information from the LED system 112 to the driver 100 in a wireless manner. Further, it is possible to use a combination of wireless data communication and wired data communication via the terminals 108, 114.

(33) According to the previous embodiments, the remote control signal has a detectable impact when measuring the load between the power terminals of the load, in case information transmission exclusively via the connection terminals 108 and 114 is used. In case of a light emitting diode unit with two power supply terminals, this detectable impact is effective for the current passing through both power supply terminals at the same time, but of opposite polarity, and can be referred to as a differential mode effect.

(34) However, it is also possible for the driver to make use of common mode effects to detect remote control signal information. In such an embodiment, the parasitic capacity of the light emitting diode unit with respect to ground potential is utilized. Such an embodiment could comprise a light emitting diode unit with two power supply terminals and a metal housing for cooling. The receiver in the light emitting diode unit is adapted to influence the coupling between the power supply terminals and the metal housing. To detect information by the driver, which information is received in the light emitting diode unit, the driver will superimpose a certain signal on the power supply terminal, preferably at a high frequency or at a high frequency alternating voltage. In case the receiver has connected one of the power supply terminals to the metal housing, the coupling capacity from the power supply terminal to ground will be higher than in the case that a sensor has disconnected the housing. By measuring the amount of high frequency current flowing through all power supply terminals, the driver can detect if there is a better or worse coupling from the light emitting diode unit towards ground potential.

(35) This measurement allows detecting whether a switch which either connects the housing to or disconnects the housing from one of the power supply terminals is opened or closed and hence provides information about the remote control signal information provided by the light emitting diode unit.

(36) In a more elaborate embodiment not only digital on/off switching but even a gradual increase of the coupling between the power supply terminal and the metal housing can be realized.

(37) According to further options, the power supply terminal is coupled to the metal housing or to other metal parts instead of the metal housing, e.g. an internal metal heat sink inside a light emitting diode system which is encased in a plastic housing, or to other electrically conductive parts like for example a conductive screening layer on the inner side of a plastic housing or an extended copper area on a printed circuit board.

(38) In a variant of FIGS. 2 and 3, the impedance emulating circuitry may be realized differently, e.g. consisting of a capacitor and a resistor, connected across a portion of the light emitting diode string, and being connected in series with the light emitting diodes and consisting of a simple inductor in case of DC driving of the light emitting diodes or a parallel connection of an inductor and/or a resistor and/or a capacitor. In all cases the frequency ranges preferably should be selected appropriately to decouple the information portion from the power supply portion of the load caused by the light emitting diode unit. According to the current stress to the component determining the volume, causes and losses, parallel structures as in FIGS. 2 and 3 are preferred.

(39) FIG. 4 is a flowchart illustrating a method of operating a light emitting diode arrangement consisting of a light emitting device system and a driver. The method starts with step 400 in which the light emitting device system is operated according to a first set of power supply characteristics, being, in the example of FIG. 4, a first frequency. In other words, the driver provides electrical power to the light emitting device system by means of an alternating current of the first frequency. After a certain time has elapsed in step 402, the driver switches for operation at a second set of power supply characteristics, being, in the example of FIG. 4, a second frequency which is different from the first frequency. The light emitting device system comprises an electric circuit which acts as an electrical load with a higher effectiveness when the light emitting device system operates according to the second set of power supply characteristics (404), being, in the example of FIG. 4, the second frequency. However, the circuitry may comprise a switch which can be turned on and off, depending on certain remote control signal information to be provided by the light emitting device system to the driver.

(40) In step 406, the driver senses the electrical load of the light emitting device system by detecting the impedance of the light emitting device system. Depending on the electrical load of the light emitting device system, in step 408 the driver adapts the power characteristics of the electrical power supply to the light emitting device system. The method continues with step 400 by switching to the operation mode in which the first set of power supply characteristics, e.g. the first frequency, is used.

(41) FIG. 5 illustrates various schematics of light emitting device systems 112. As shown in FIGS. 5a, b and c, each light emitting device system comprises a housing 500 which comprises a system board 506. Mounted on the system board 506 are at least one light emitting diode 116 and an emulation module 120. Further, the LED system 112 comprises an optical lens 502 which may be used to concentrate the light emanated from the light emitting diode(s) or to expand the light beam emanated from the light emitting diode(s) 116.

(42) In all embodiments of FIGS. 5a, 5b and 5c, a remote control signal receiver 118 is located in a surface area of the light emitting device system facing in a direction 510 of the illumination beam path of a light cone 508.

(43) It is also possible to have a different orientation of the sensor. E.g. a sensor with omnidirectional sensitivity can be placed on a surface having any orientation, as long as a direct or reflected line-of-sight between the desired remote control transmitter position and the sensor is possible.

(44) In FIG. 5a, the remote control signal receiver is mounted on the system board 506 and located between two light emitting diodes 116. As a consequence, the remote control signal receiver is not located in the illumination beam path 510 facing in the direction of the illumination beam path 510. As a consequence, especially in case the receiver 118 is an optical receiver, such as an infrared remote control signal receiver, any IR remote control signal pointing within the light cone 508 towards the light emitting device system 112 will be sensed by the receiver 118. In a more illustrative manner, any object which is illuminated directly by the light emitting device system 112 may be used as transmitter position for a remote control transmitter since, in this case, the remote control transmitter and the receiver 118 are in the direct line of sight.

(45) In the embodiment of FIG. 5b, the remote control signal receiver 118 is located in the illumination beam path 510 of the light emitting device system. More precisely, the remote control signal receiver 118 is located on an optical axis 512 of the lens 502. On its rear side facing the LED 116, the remote control signal receiver 118 carries a mirror 514. Light which directly emanates from the LED 116 towards the mirror 514 on the optical axis 512 is reflected towards a parabolic mirror 504 which is arranged on the system board 506 around the LED 116. Since the mirror 504 is a concave mirror, the LED system 112 in combination with the lens 502 can be used for providing a directed and highly parallel beam in the direction 510. At the same time, the remote control signal receiver 118 is always visible for an infrared remote control transmitter, since no shadowing of the receiver 118 by other parts of the LED system 112 takes placet.

(46) In the embodiment of FIG. 5c, the remote control signal receiver 118 is located in the surface area of the LED system which faces in the direction 510 of the illumination beam path of the light emitting device system. Here, the remote control signal receiver is mounted to the housing 500, which has similar advantages to the receiver position discussed with respect to FIG. 5b.

REFERENCE NUMERALS

(47) 100 Driver 102 Power supply 104 Controller 106 Detector 108 Terminals 110 Cable or rail 112 Light emitting device system 114 Terminals 116 Light emitting diode 118 Receiver 120 Emulation module 122 Controller 124 Circuit 126 Network 128 PC 200 Amplifier 202 IR photodiode 204 Resistor 206 Transistor 208 Circuit 210 Receiver unit 300 Antenna 302 Impedance 304 Capacitance 306 Variable resistor 308 Circuit 500 Casing 502 Optical lens 504 Mirror 506 System board 508 Light cone 510 Illumination beam path 512 Optical axis